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#1
BZero

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Just some quick , simple questions that I want to get cleared up.

NAD 1983 stateplane and NAD 1983 stateplane (feet). Aren't stateplane units always feet? So the only difference between these is?

HARN coordinate systems. Should they always be used over the regular NAD 1983. The information I read says it is more accurate due to GPS validation. However, it seems like the people I am around are still using regular NAD 1983. Is it just that more datasets are still in this datum then the latter that it is used more often?

#2
Esther Mandeno

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Just some quick , simple questions that I want to get cleared up.

NAD 1983 stateplane and NAD 1983 stateplane (feet). Aren't stateplane units always feet? So the only difference between these is?


If it's not stated, then I usually assume it is in feet, but it can be in other units (most often meters). Just depends on how they define it.

HARN coordinate systems. Should they always be used over the regular NAD 1983. The information I read says it is more accurate due to GPS validation. However, it seems like the people I am around are still using regular NAD 1983. Is it just that more datasets are still in this datum then the latter that it is used more often?


What is the context in which you are asking this question? The reason I ask is that it depends on who you are working with and sharing your data with. Counties most often use NAD 1983, so I just use what they use, but if you are the only one using the data, then use what suits your needs.

I'm sure there are more competent folks on this forum that can answer these questions better, but there you go. :)
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Esther Mandeno
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#3
johnnyh

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Stateplane units can be defined and projected as either... I've ran across both meters and feet. State plane seems to be popular with state agencies, go figure.

The USGS and all other Fed agencies I've worked with all use NAD83, with older data in NAD27 still hanging around sometimes... In natural resources, use of HARN doesn't seem widespread. At least in my limited experience.

Just some quick , simple questions that I want to get cleared up.

NAD 1983 stateplane and NAD 1983 stateplane (feet). Aren't stateplane units always feet? So the only difference between these is?

HARN coordinate systems. Should they always be used over the regular NAD 1983. The information I read says it is more accurate due to GPS validation. However, it seems like the people I am around are still using regular NAD 1983. Is it just that more datasets are still in this datum then the latter that it is used more often?



#4
Patrick

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Just some quick , simple questions that I want to get cleared up.

NAD 1983 stateplane and NAD 1983 stateplane (feet). Aren't stateplane units always feet? So the only difference between these is?

HARN coordinate systems. Should they always be used over the regular NAD 1983. The information I read says it is more accurate due to GPS validation. However, it seems like the people I am around are still using regular NAD 1983. Is it just that more datasets are still in this datum then the latter that it is used more often?


Most of this is only of concern to survey quality data where a difference of .1' can be a big deal. From a mapping perspective it is negligible.

State plane is realized in both feet and meters. the NGS (National Geodectic Survey) does all their work in metric and supplies US Survey Foot values for convenience. Again, from a surveyors perspective care has to be taken when going from Meter to Feet as in reality there are two foot units and some states use one while others use the other. The US Survey Foot is defined as 1 ft = 1200/3937 m and the International Foot is defined as 1"=2.54cm. Seems insignificant but when you are scaling a large metric state plane coordinate (eg. N:500,000 E:500,000) to feet it can make a significant difference. Once again mostly from a surveying perspective.

For any non-surveying application HARN is NAD83. There is a whole bunch of good info at http://www.ngs.noaa.gov/faq.shtml if interested.




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